1. Field of the Invention
The present invention relates to a disaster prevention monitoring apparatus and method which collects terminal information in response to a call from a receiver end to collectively monitor an abnormal status such as a fire.
2. Description of the Related Art
An example of a conventional disaster prevention monitor is disclosed in Examined Japanese Patent Publication No. HEI. 4-64713. In the disclosed disaster prevention monitor, when an abnormal status at a terminal, such as when a terminal fails to reply to a call from a receiver, is detected, the receiver commands the terminal to transmit information as to the type of the terminal (hereinafter referred to as "type information").
Specifically, an occasion may occur in which one sensor is replaced by another sensor of a different type after the disaster prevention monitor is powered on. When the old sensor is removed and no reply is made to a call from the receiver, the receiver commands the terminal to transmit type information, whereby type information is obtained from the new sensor and transmitted to the receiver (also referred to as a central station). In accordance with the type information, the receiver again initializes information relating to the sensor and stored in the receiver.
In such a conventional disaster prevention monitor, however, a plurality of sensors are sequentially called in accordance with a polling sequence controlled at the receiver. Where the number of sensors is very large, the polling period will be very long, and it is possible that a sensor can be replaced by a new sensor within the time between successive pollings of the sensor. In such a case, the receiver will not know that the sensor has been replaced and, as a result, will not enter a mode to initialize to the new sensor.